I am having a very strange issue and have done extensive troubleshooting myself but cannot find a solution. I have two Tivo HD units both upgraded with 500GB drives and using cable cards on Comcast.
When I click "Video On Demand" on the Tivo Central screen I get the following message instantly (almost no delay and no network activity) "There was a problem accessing the video on demand screen. To resolve this issue, please try the following" It then lists step one, make a tivo service connection and step two to go to the support site.

I have tried the following to troubleshoot this issue:
1. Tivo service conenction and reboot on both units (same issue on both DRV's)
2. Verify opt and video download status on Tivo.com (yes I have tried disabling, conencting and then re-enabling)
3. Tivo network diagnostics under messages and settings (indicates nopproblems with open ports or DHCP)
4. Connecting Tivo directly to my cable modem, assigning public IP address via DHCP, doing tivo service conenction and then reboot
5. Bringing one of the DVR's to a friends house where they have a workign Tivo with video on demand functional
6. Pause 52 software reload
7. Repeat guided setup - I did not yet try clear and delete everything

Here are some other facts about this issue:
1. I can access you tube just fine under Music, Photos and Showcases
2. I still recieve pushes for video on demand content I subscribe to
3. I can get to netflix and it works but only if I click the advertisement for it under messages and settings on tivo central
4. Clicking the ad for order dominos pizza from tivo central brings me to a screen with an option to "get broadband" and doesnt let me order
5. Swivel search gives a network unavailable message, however Tivo search beta under showcases works fine

I AM AT MY WITS END. Anyone have any ideas? I was thinking as a next step, clear and delete everythign but I want that only as a last resort.

Anyone have any ideas on this? Tivo support is now refusing to help further because the unit was upgraded with a 500gb drive and they are blaming that. I have the 160gb back in now and updated it to the latest software by doing a service connection. SAME ISSUE

For kicks I reactivated my old series 2 and video on demand works fine. Also I did clear and delete everything on one of the HD Tivo's. This did not fix the problem.

I'm thinking that they messed something up on my account when I called to opt out of anonymous data collection before. (I'm opt-full now and have been for over a week) I cant imagine what else this could be.

At this point I am considering canceling my service on both DVR's and just getting a Comcast DVR (which I am fully aware stink, trust me) simply because i'm annoyed with Tivo's lack of responce and refuse to believe both units I have developed the same software/hardware defect (unrelated to anything Tivo did) at the exact same time.

So turns out it's a bug for sure and there is a simple, but slightly annoying fix that takes about 45 minutes to apply and your back in business. I have reported this to a supervisor at Tivo and they are notifying all the reps.

The following fix worked for my Tivo HD boxes. It is the result of over 7 calls to tivo (no help from them) and hours of trying things... :-)

1. Disconnect the network cable
2. Plug in a telepohone line. (sadly this is a necessary step) a POTS line works the best, VOIP is hit or miss.
3. Switch the Tivo to use a phoneline connection under phone and network settings. Let it make 2-3 tivo service connections using the phone line.
4. Go back to Tivo central and then unplug the Tivo for 10 minutes
5. Reboot with the phone line plugged in and no network cable or wireless adapter conencted.
6. Look on your tivo Central screen. Showcases should be gone. If it's not, do a few more service connections and maybe another reboot. It also may take some time for the tivo to process everything. The goal is to make "Music Photos and Showcases disappear from Tivo Central.
7. Once showcases is no longer listed, your ready for the final steps. DONT try these before showcases disappears or it wont work
8. Plug in a network cable and in phone and network settings switch the tivo back to use a network connection.
9. Perform connect to tivo service now
10. Showcases will re-appear and after loading is complete, network features and video on demand work!!!

I wonder how I am supposed to fix this without a phone line. I keep having the same problem and have forced the Tivo connection multiple times. The software is up to date and I had a glimpse of Netflix on there once, then it froze and now I just get 'There was a problem accessing the video on demand screen.' This seems to be a common problem in a number of threads, anyone find a good solution yet?

One other thing, I have very basic cable and so I have not aquired a cable card. Is this necessary in order to use the Netflix Video on Demand feature? Youtube works fine and I can access Amazon VoD through Showcase (although I have not purchased/viewed any yet).

I am having the same exact issue and I do not have a phone line. I have put in calls to Tivo and they are blaming my firewall. I have removed the firewall and the issue remains. If anyone figures this out, please post it here so we can all learn from your solution.

I am having the same issue. Up until today, I was able to access the video on demand but today it gives the same error message. I do not have a phone connection so I can not try what is suggested. Anyone has any other suggestions ?

I had the same issue this morning when setting up something for my daughter to watch on Netflix. There was no Netflix folder in the Now Playing list and I got the above error when accessing VOD. I followed the instructions for a service connection and then everything was working fine.

I started having the problem (unable to navigate Video on Demand or TIVO Search) in just the past few days. Sort of hit or miss, sometimes unexpectedly reverting to Main screen while in the process of navigating or just unable to navigate at all to those two functions.

I'd been moving furniture, modems, Series 3 Tivo box, TV, etc. due to a house remodel (But that's a whole 'nuther story). Anyway, at least for now, a simple "hard" re-boot of the TIVO Series 3 box cleared it up. By "hard boot" I mean unplug the power cord, give it a minute or two, then power up again, letting it go thru its reboot routine.